Truck with interrelated multiple prime movers, power take-off couplings, and operating controls therefor



v 2,689,621 s, POWER B. G. DONLEY Sept. 21, 1954 TRUCK WITH INTERRELATED MULTIPLE PRIME MOVER TAKE-OF`F COUPLINGS, AND OPERATING CONTROLS THEREF'OR 13, 1947 4 Sheets-Sheet l Filed sept.

2,689,621 POWER 4 Sheets-Sheet 2 Sept 21, 1954 B. G. DoNLEY TRUCK WITH INTERRELATED MULTIPLE PRIME MOVERS TAKE-OFF COUPLINGS, AND OPERATING CONTROLS THEREFOR Filed sept. 15, 1947 INVENT'E 2,689,621 POWER DONLEY MULTIPLE PRIME MOVERS,

4 Sheets-Sheet 3 TRUCK WITH INTERRELATED,

TAKE-OFF COUPLINGS, AND OPERATING CONTROLS THEREFOR Sept. 21, 1954 Filed Sept. l5, 1947 Sept. 2l, 1954 B. G. DONLEY 2,689,621

TRUCK WITH INTERRRLATRO MULTIPLE PRIME MOvERs, ROwER TAKE-ORF cOuPLINGs, ANO OPERATING CONTROLS TRERRFOR Filed Sept. 13, 1947 4 Sheets-Sheet 4 ATTORNEY! Patented Sept. 21, 1954 TRUCK `WITH INTERRELATED `MULTIPLE PRIME MOVE-RS, POWER TAKE-*OFF COU- PLINGS, AND OPERATING CONTROLS THEREFOR Bartrum vGr.'Donley,A'Clintonville, Wis., assignorto The vFour Wheel Drive Auto `Company,-Clinton ville, Wis., 'a corporation of Wisconsin Application September 13, 1947, Serial No. 773,780

18 Claims. 1

This invention relates to improvements in trucks with multiple prime movers, `the `particu lar device disclosed being specifically designed for use for cementing oil well casings.

One of the important Vobjects of the'present invention is to provide a truck having a plurality of prime movers arranged in a novel organization behind the truck cab, and 'cross connections whereby both engines may be used to drive equipment mounted on the truck, or either engine may be used either for the propelling of the truck or to .drive a partof such equipment. In connection with this object, it is a further `purpose to provide suitableinterlocking pneumatic controls for the several driving connections `and clutches.

It is a further important object of the invention to provide a means whereby the gear shift transmission normally employed in driving the truck is alternatively usable for the drive of ancillary equipment mounted on the truck and, accordingly, is provided with controls operable either from the truck cab, or from an operators station behind the cab on the bed `o'f the truck. It is my further purpose to provide suitable means for selecting the position fromwhich the transmission will be operable, the selecting means being so designed that the gear 'shifting rods may be operatedfrom one station or the other, but not from both simultaneously.

` VIt is a further -object of the invention to provide a novel'engine mounting and a novel Atruck frame for accommodating the engines and their cross connections.`

The foregoing statement of objects identifies the purposes of the invention only broadly. For a detailed explanation of my purposes, reference is made to the accompanying drawings .and the following description.

In the drawings:

Fig. 1 is a plan `view of a truck` embodying my invention, omitting the caband body, vand upon which I have superimposed a diagram of the pneumatic control system. i

Fig. 2 is ra view in vertical longitudinal `section on ythe line 2--2 o'f Fig. 1.

Fig. 3 is a view of the truck inrightside`ele` vation.

i Fig. 4 is a view in transverse section on `the line 4-4 of Fig. 1.

Fig. 5 is a view of the station selector yin side elevation.

Fig. t3` is a view of fthe station selector infront elevation.

Fig. 7 is a diagrammatic plan view of the torque `changer l and its control.

Fig. 8 is a diagrammatic view Vin vertical section through the forwardmost of two `similar chain transmission casings.

As bestshown in Fig. 3, the truck frame has a dropped central section at 8. The front portion 9 and the rear portion I0 of the truck frame are `conventionally made of side channels having their flanges turned inwardly. These channelsare'bent downwardlyat II and I2 respectivelyand welded back'to back with side channels. which have their flanges turned outwardly.

The side channels lil are connected by suitable transverse members as required and are provided with outboard brackets I3 and I4 for the radiator end and output end respectively of the respective prime movers I5, I6. These heavy duty internal `combustion engines are thus carried with their lines well offset outwardly fromy the sides `of the frame and ata relatively low level 4made possible by the dropped frame sections 8.

As will be observed in Fig. 1, the engines face in oppositedirections, the radiator Il of prime movery I5 being disposed rearwardly, while the radiator I8 of prime mover I6 is disposed forwardly. The `engines are also slightly offset in a direction longitudinally of the truck, the engine I5=being farther to-the rear than engine IB.

Between the two engines, in a position `gen erally conventional on four wheel driveY trucks, is the gear shift transmission 20. The power output from transmission 20, `as determined by the conventional combinations of Ygear pairs therein, passes through van output clutch 2| whereby the power may be selectively delivered either toa power take-'off shaft '22,or through a conventional chain transmission case 23 to the line shafts 24, 25 leading tothe respective differentials of the frontV and rear axles. The general organization of such a transmission is shown in U. S. Patent No. 2,395,108.

The `power communicated through the change speed transmission 2Iito the wheels ordinarily comes from the prime mover I 5.` The heavy dutyengine I 5.drives, through a hydraulic clutch 2'I` and `frictionr clutch 2'8, `an output shaft 28 connectedV through meshing reverse gears 280 and 28| the input sprocket 29'in a generally triangular chain drive housing 3U. AThe chain 3I therein passes about sprockets 29, 32 and 33. Sprocket 32 is 4at the top of the housing, and sprocket 33 at the lower inside corner. Sprocket 3 33 connects directly with the input shaft 34 which drives the gear shift transmission 20.

Prime mover I6 has its crank shaft 35 selectively engageable by means of clutch 36 with the drive through the torque converter turbine diagrammatically shown at 31 (Fig. 7),- or, alternatively, in direct drive connection with the output shaft 38. rilhe rotor 39 which communicates the output of the torque converter 31 has an over-running clutch connection at 40 with output shaft 38, so that when clutch 35 is engaged with the input rotor 4I to drive through the torque converter, the output motion from the torque converter will be transmitted to shaft 38. Rotor 3S and the torque converter 31 will, however, be idle when the clutch 35 is in position for direct drive to shaft 38. The torque converter is merely illustrated diagrammatically, since it comprises no part of the present invention. It is illustrated only as a means of showing how it is connected by means of its operator 42 to effect the operation of the pneumatic controls hereinafter to be described.

The output shaft 38, driven from crank shaft 35 of engine I5, drives the input sprocket 44 in the chain transmission case 45. This transmission case is similar to that shown at 35. Its transmission chain 45 operates over sprockets 44, 41 and 48. The sprocket I41 is mounted on a power take-off shaft 49 at the lower inside corner of the transmission case. Sprocket 43, mounted on its stub shaft 48. is at the top of the generally triangular transmission case 45.

During the operation of the truck in cementing an oil well casing, the power take-off shaft 22, ordinarily driven from engine I through the change speed transmission 25, drives the input shaft of a high pressure pump 50. The power take-off shaft 49, ordinarily operated from engine I5 through the mechanism just described, drives the input shaft of a low pressure pump 5I.

A cross connection is provided whereby either engine can operate the truck, and either engine may be employed to operate either o-f the pumps. It is extremely important that the two engines shall selectively be available to operate either pump, inasmuch as power failure during the actual cementing of an oil well casing might have disastrous results.

The cross connection between the two units is provided by means of a clutch at 52 whereby the top chain sprocket 32 of the forward chain transmission case 33 may be engaged to drive an output shaft 53 at the top of such case. Similarly, a clutch 54 may be engaged to enable the top sprocket 48 in the rearward chain transmission case 45 to be coupled to the exibly jointed cross shaft 55 which transmits motion from either engine to the parts normally driven by the other. The means by which the respective clutches are provided with interlocking controls will hereinafter be described. For the present, it is desired to note that with the clutch 28 of engine I5 disengaged, power may be transmitted from engine I5 lthrough the rearward chain transmission case 45 and the cross shaft 55 and forward chain transmission case 30 to the gear shift transmission 2l! and thence, .at a rate determined by the gears therein, either to the drive shafts or to the high pressure pump 5D. Similarly, with clutch control 42 in its neutral positio-n and clutches 52 and 54 engaged, power may be transmitted from engine I5 through the forward chain transmission case 35 and the cross shaft 55 and the rearward transmission case 45 to the low pressure pump 5 I. While these pumps are referred to as high and low pressure pumps, it will be understood that this term is relative. For the particular intended purpose, the high pressure pump develops up to twelve thousand pounds per square inch, and the so-called low pressure -pump develops up to seven thousand pounds per square inch.

It will, of course, be understood that the present invention is by no means limited to the operation of concrete pumps, but may be employed to operate any ancillary apparatus mounted on a truck or otherwise.

For operating the various clutches and also providing an interlock to preclude improper operation thereof, I have a system of uid controls which, as illustrated to exemplify the invention, use air pressure from an air tank 51. Air may be pumped into the tank 51 from any desired source, as, for example, from an air compressor (not shown) driven by engine I5. An air supply line 58 runs from the tank to the engine cab 59 within which a number of the controls are located. A branch pipe 60 leads to a control valve 6I for selectively delivering pressure into either of the lines 62 or 53. Each of these lines divides and leads to the corresponding ends of double-acting cylinders 54 and 65, wherein pistons are operable as indicated in dotted lines. The piston in cylinder 54 is operatively connected to .actuatethe clutch 2 I, While the piston in cylinder `65 is operatively connected to actuate a, selector mechanism for the controls which shift the gears in the change speed transmission 26. The selector mechanism will be later described. Its purpose is to enable the gears in the transmission case 20 to be shifted either from the cab, or from the operators station at the rear of the truck. The pneumatic connections are such that when the gears are capable of being shifted from the cab, the clutch 2l is simultaneously shifted to disengage the power output of the transmission 2B from the take-olf coupling 22, and to clutch the transmission 20 to the drive through the chain case 23 to the respective wheels. Conversely, when the control cylinder 65 is pneumatically energized, the selector is positioned to permit operation of the gears in the case 2D, from the rear of the truck. The clutcth 2I is simultaneously shifted by the pneumatic energization of cylinder 64 to de-clutch the gear transmission 20 from the wheels and to clutch the gear transmission tothe power take-off 22.

The three-way valve at 61 receives high pressure air through the branch line 68 and delivers such air selectively through lines 69 or 10, according to the position of the valve. The line 69 divides, communicating with lines 1I and 12, each of which is provided with a check valve 13, 14 through which the air will pass freely in a direction away from the control valve 61. From check valve 13, the air follows line 1i5 to another check valve .at 16 and then follows line 11 to the pneumatic cylinder 18 which disengages clutch 28 of engine I5. From check valve 14, the air also passes through lines 19 to branch lines 80 and 8I. Line 80 leads to the control cylinder 82 for clutch 52. When the cylinder 82 is pneumatically energized, the clutch 52 is engaged to couple sprocket 32 in the forward chain transmission case 30 with the outputs shafts 53, 55. The branch line 8| leads to the pneumatic cylinder 83 which, when pneumatically energizing,

shifts clutch 54 toengage sprocket 48 in the rear chain transmission casing 45 with the cross shaft 55. Thus, the simultaneous energization of cylinders 32 and 83 will engage both clutches and complete a cross drive between the two transmission chains, at the same time disengaging engine I from the transmission chain y3| in the forward case 30. This establishes engine I8 as a source of power for driving through the change speed transmission 20 either to the take-off coupling 22, or the wheels of the truck, according to the adjustment of clutch 2|.

Assuming the control valve 61 to be swung to `its opposite vposition whereby air is supplied to line 10, such air will pass through check valve 84 into lines 19, 80 and 8| to energize the cylinders 82 and 83 for engaging the cross shaft clutches 52 and 54 as already described, In addition, however, the air will pass through line 85 to a valve 420 which is associated with the rock shaft 42 which shifts clutch 36 either for direct drive, or drive through the torque converter from engine I5. The valve 420 has two relief ports at 8G and 81 respectively. When the clutch shifter 94. is in its neutral position, the valve 420 is closed and does not afford communication between line 85 and either of these relief ports. However, if the clutch shifter 94 is moved in either direction to engage either clutch, the valve 420 will place line 85 in communication with one or the other of the relief ports to bleed pressure from line 'I0 and thereby to preclude the pneumatic engagement of clutches 52 and 54 from line 10. Thus, the purpose of valve 61 is to preclude the engagement of the cross shaft clutches `52 and 54 when engine I6 is`being controlled from the rear station. With Valve B1 in the position first described, the cross shaft clutches 52 and 54 may be engaged to transmit the power of engine `I5 through the cross shaft.

.sure through line 'I0 to the bleed valve 420.

To enable the clutch of engine I5 to be controlled from the rear station, a separate line 68 from the air tank 51 leads through control valve 89 at the rear station, through the line 90 which communicates through check valve 9| with line 11 to the operating cylinder 'I3 for friction clutch 28. Also disposed at the rear station is a manual control 92 having linkage diagrammatically illustrated at 93 which leads to a lever 94 connected with rock shaft 42 and valve 420 Thus, from the rear station, the clutch 36 of engine I6 can be set in neutral, and when it is in neutral, with valve EI set for control of the gear shift from the rear station, the clutches 52 and 54 and 28 may all be engaged for transmission of engine power from engine I5 through the two chain transmission cases 30 and 45 and the intervening cross shaft 55 to the power take-off coupling 49.

Engine clutch 23 may also be controlled pneumatically from the clutch pedal 95 which operates `a valve diagrammatically shown at 90 controlling communication from the pressure line 58 through conduit 9'I and check valve 98 to line "I5, whence pressure is communicated to the clutch actuator 6 from more than one valve, and each has fits origin betweena pair of check rvalves which-are oppositely directed to permit the air to enter the line to the respective clutch actuating cylinder from either direction by precluding any back pressure from leaving such line in the opposite direction.

Projecting forwardly from the top of the change speed transmission case 20 are the usual gear shifting plungers |00, |0I, |02 (Fig. 6). It is customary to operate such plungers by linkseX- tending into the cab, and there selectively picked up for operation by the usual gear shifting lever (not shown). Links comprising a part of=a system of linkage leading to the cab are illustrated at |03, |04 and |05 respectively. Corresponding links |06, |01 and |08 `comprise part ofla suitable system of linkage running to the control station on the rear of the truck. Itis not deemed necessary to show the manner in which these links are conventionally operated by the shifting levers, as such operation is well-known.

As already explained, it is desirable to provide means whereby the gear shifting plungers |00, |0| and |02 `may be operated either `from the cab, or from the rear control station, but not from both simultaneously. To this end, I have provided a selector mechanism best shown in Figs. 5 and 6.

In this system, a vertical lever |09 is connected at its lower end with the gear shifting 'plunger |02, and at its upper end withlink |05. At an intermediate level, the lever |09 `has pivotal connections with the -operating link |08 from the rear control station.

Similarly, the central lever I|0 is connected at its bottom with plunger IIlI, and centrally with link |91, and at its top with link |04. The remaining lever I I is connected at its bottom with plunger |00, centrally with link |06, and at its top with link |03.

The several levers have transversely registering arcuate slots ||2 which are concentric with a pintle I3 upon which the bell crank I4 is` oscillatable. This bell crank has its end pivoted to connecting rod I5 which is carried by piston `H0 operating in cylinder 65. Pressure admitted to the cylinder through line 62 operates the piston to the right as viewed in Fig. 5 to oscillate the bell crank ||4 counterclockwise, while pressure admitted through the line 63 actuates thebell crank I I4 clockwise. At the other end of pintle ||3 is a rocker arm II'I. The bell crank ||14 and rocker arm II'I carry from pintle ||3 a floating pintle |20 which extends 'through the registering slots ||2 of the several levers. When the bell crank |I4 is in the position shown in full lines in Fig. 5, the pintle |20 registers with the several links |03, |04, |05 which lead from the cab. When the bell crank ||4 is in the position shown in dotted lines in Fig. 5, the floating pintle |20 is at a level such that it registers with the several links |06, |01 and |08 leading from the rear control station.

It Will be evident from an analysis of Fig. 5 that with the floating pintle in its uppermost position as shown in full lines, the front control links cannot actuate lever |09 because they register with the pintle upon which it is then ful- Crumed. However, the rear control links may readily be manipulated from the rear control station to shift their respective levers and thereby to actuate the respective push rods or plungers for shifting the gears in transmission 20.

With the bell crank I I4 oscillated tothe dotted line position of Fig. 5, the floating pintle |20 now registers with the links from the rear control station, making it impossible for these links to move and to operate the lever |09. However, it is now possible to manipulate any of theselevers from the front control station by actuating the proper link and thereby oscillating the appropriate lever about the floating pintle to shift the corresponding gear shifting plunger.

The operation of the truck from the front and rear stations is as follows:

Front station- This station is used primarily to control the movement of the vehicle. From this station the Wheels may be powered from either of engines or i0, and the gears in transmission 20 shifted by rods |03, |04 and |05. Valve 6| is set to engage transmission 20 through clutch 2| to the drive wheels through chain case 23. Such setting simultaneously sets the selector mechanism shown in Figs. 5 and 6 to prevent control of the transmission from the rear station, and disengage the take off coupling 22 from clutch 2 With no further manipulation of the controls the vehicle is powered from engine I5. If however, the manual control 92 at the rear station be preset for power transmission from engine I6 to the output shaft 33, engine |5 may be disengaged and engine It engaged for Vehicle drive through cross shaft 55 by setting valve 5l to pressurize line 69, which simultaneously actuates clutch actuator I8 and the clutches 52 and 54 in the manner aforesaid to disconnect engine I5 and connect engine I6.

Rear station-This station is used primarily to control the equipment powered from the takeoff shafts 22 and 49. Valve 6| is first set to engage transmission 20 through. clutch 2| to the take-off shaft 22, thereby inactivating the drive to the wheels. Transmission 20 is then controlled from the rear station through rods |06, |01 and |08, and control of the transmission from the front station is prevented. If valve 6l be preset to off position, clutch 52 and 54 will be disengaged and engine l5 will power only shaft 22. If valve 61 be preset to pressurize line 10, and if the clutch shifter 42 be in neutral position, clutches 52 and 54 will be engaged and engine l5 will be connected both to take-olf shaft 22, through the transmission 20, and to take-olf shaft 49, through cross drive shaft 55. To transfer input to shaft 45 from engine l5 to engine I6, manual control 92 is set to engage clutch 36,

` either directly or through the torque converter 31, to shaft 38. Air will simultaneously be bled from line through port 420 to disengage clutches 52 and 54 in the manner aforesaid, whereupon engine i6 drives shaft 49 and engine I5 is disconnected therefrom. If it is then desired to cut the power to shaft 22, valve 89 may be set to pressurize line 90 which, through clutch actuator 18, declutches engine i5.

If it is desired that engine i9 power only shaft 49, valve B1 is preset to off position thereby inactivating clutches 52, 54. Power is then delivered by engine i6 to shaft 49 only. If line 90 be simultaneously pressurized, thereby declutching engine I5, only shaft 49 receives power. If it be desired to power both take-off shafts 49 and 22, from engine I6, valve 67 must be preset to pressurize line 59, whereupon the setting of manual control 92 will have no effect on the clutches 52 and 54 which will be permanently engaged. In this arrangement engine |5 is disengaged by pressurizing line 90 to declutch clutch 28, as aforesaid, and both couplings 22 and 49 will receive power solely from engine I6.

It will be apparent from the foregoing description that I have provided a duplex power plant with multiple power outlets and cross connections for enabling either outlet to be actuated from either source of power. It will also be evident that I have provided arrangements whereby the various connections may be operated from two distinctly separate control stations to actuate power outlets appropriate for those stations.

I have also provided interlocking controls whereby the mechanism is protected from improper operation when the intended regulation is set up for control from one station or the other. In some instances, the interlock is pneumatic, while in other instances it is mechanical. Where the interlock has been adequately effected, there are some instances in which it is brought about by the positive shifting of some part, while, in other instances, the interlock is effected by bleeding olf the air pressure to preclude operation in the event of an improper hook-up.

The disposition of the truck engines not only facilitates their cross connection for the stated purposes, but has advantages in the operation of this type of truck in that the engines are entirely accessible, and the cab can be. located in a relatively low position in the extreme forward end of the truck. The engines are not only balanced, but, due to the drop frame, the forward chain transmission 30 can be located at a level to drive directly from the outboard engine to the shaft input of the speed changing transmission 20 without displacing such transmission from its normal position in a four wheel drive truck.

I claim:

1. A duplex power plant comprising a pair of parallel engines side by side and reversed end for end, each engine being provided with an output shaft and a clutch having parts connected to said engine and said output shaft, a pair of output transmissions, each comprising at least three rotors and motion transmitting connections in driving connection to said rotors, the output shaft of each engine being connected to one rotor in respective transmissions, power take-olf couplings operatively connected with a second rotor in each of the respective transmissions, clutches connected to the third rotors of the respective transmissions, and a cross shaft independent of the output shafts and connected t0 the third rotor clutches of both transmissions, said cross connection comprising means whereby each transmission and power take-olf may be actuated by either engine.

2. A multiple engine combination comprising a pair of engines having output shafts, clutches connected to each of said output shafts and to said engines whereby respective output shafts may be controlled, a pair of transmissions, each including at least three sprockets and chains connecting the respective sprockets, one sprocket of each transmission being connected with the output shaft of each engine, power take-off couplings connected with a second sprocket of the respective transmissions, a cross shaft and a clutch connected to each end of said cross shaft, said clutches being also connected to the third sprockets of each transmission, said cross shaft and clutches comprising means whereby each power take-01T coupling may be driven from each engine.

i trols operatively' connected withi the respective cross. shaft clutches andi regulating the operation thereof to selectively preclude simultaneous iinterlock comprising: fluid lines having terminal Acylinders and pistons mechanically connected with the respective cross shaft clutches, and valvesl insaidlines lfor. selectively controlling said lines.

5. The combination' with a plurality of power take-off couplings, ofV pluralV means' for driving lthe :respective couplings and comprising separate engines havingpower output shafts :and clutches i controlling'said shafts, motion transmitting conrnections fromthe respective shafts to the respective couplings, and a cross connection including a clutch between'said` said motion transmitting connections, together with a fluidapressure control system for said cross connection clutch comprising a clutch operating cylinder, a piston therein provided. with a `link connected to the clutch, a fluid pressure line to the cylinder, and a control valve regulating pressure communication throughsaid'line.

` 6. The combination with a plurality of engines and a plurality `of power output shaftsand driving connections from the respective engines to the respective shafts, and a crossconnection for couplingeach engine to the shaft normally driven from the other, of clutches controlling the said driving connections and'a clutchcontrolling said cross-connection, operators for. the `respective clutches, the operator `for the cross connection clutch comprising a nuid'cylinder and piston, and the drivingconnection clutch operators having a valve connected thereto, said valve including a bleed port andal valvemember, said valve member being connected to bleedpressure from the cross connection clutchfcylinder when `the'clutch operator with whichwthe valvemember is connected is` in clutch-engaging position.

'7. In a truck, a frame having supporting axles and wheels across which said frame extends ap* proximately horizontally, said frame having side members at a lower level between said wheels than at said wheels and toward which side members at said lower level both ends of said frame are curved downwardly, said frame having side members at its respective ends comprising channels with inwardly directed flanges, and the side members at a lower level comprising channels with outwardly directed flanges, the respective channels having means connecting the downwardly curved portions aforesaid to the channels with outwardly directed anges back to back.

8. A truck comprising a frame provided with fore and aft portions, each having side frame members, and a dropped central portion having side frame members at a lower level than the side frame members first mentioned and connected therewith, a change speed transmission mounted between the side frame members of the dropped portion and having a power input shaft, brackets mounted on said last mentioned side members and projecting laterally outwardly from the frame, engines mounted on said brackets, one of saidengines being provided with a clutch-controlled sprocket, a second sprocket connected with 10 the input shaft of said transmission, athird sprocket, a chain passing about the three sprocketsfor motion transmission therebetween, and a` clutch-controlled cross connection independent of the engine drive shafts from the other engine to said third sprocket.

9. The combination set forth in claim 8 in further combination with a power output coupling, a truck drive shaft, and clutch-oontro1led connections from said change speed transmission to said coupling and drive shaft respectively.

10. A multiple power plant comprising a plurality of engines, a plurality of output couplings, drive connections from each engine to its respective coupling, a plurality of drive connection clutches having parts connected to said engines and parts connected to said drive connections for the control of said drive connection, across connection having connections to the drive connections aforesaid whereby each engine may be coupled to either coupling, a plurality of control stations, drive connection clutch controls at the respective stations, andinterlocking connections to said drive connection clutch controls.

11. In a device of the character described, the combination with a truck frame having forward andrearward control stations, of a change speed transmissionzhaving a control plunger, plungeroperating linkage leading toward said plunger from the respective stations, and a selector, means for connecting said plunger and linkage, said selector beingconnected to said linkage, said selector comprising interlock means for selectively rendering the linkage from one of said stations operative upon the plunger while at the same time renderingthe linkagefrom the other station inoperative thereon.

12. The combination set forth in claim 11 wherein said change speed' transmission comprises a power takeoff shaft and a truck drive shaft, a clutch having parts connected to said power take-off shaft and said truck drive shaft for selectively coupling one of said shafts to the transmission, and an operating connection from said selector to said last mentioned clutch for shifting saidclutchto a position dependent upon which linkage is operative upon the plunger.

13. Thedevice of claim 11` in which a lever is pivotally connected with the linkage fromV the front control station and with the linkage from the rear control station and with said plunger, said lever having an adjustable fulcrum at said selector comprising means connected with the fulcrum for adjusting said fulcrum from registration with one linkage to a position of registration with the other.

14. In a device of the character described, the combination with a member to be operated and a plurality of separate operating connections therefor, of a lever with which said member and the respective connections are pivoted at spaced points, an adjustable fulcrum upon which said lever is pivotally movable, and a selector coinprising means connected with said fulcrum and moving said fulcrum from a position of substantial registration with one of said connections to substantial registration with the other.

15. In a device 0f the character described, the combination with two operating rods and an operated rod, of a lever with which the several rods are in pivotal connection at spaced points, said lever having a slot extending substantially from the pivotal connection of one of the operating rods with the lever to the pivotal connection of the other operating rod with the lever, a selector prising a plurality of shiftable rods for gear shifting purposes, of'levers pivotally connected with the respective rods and provided at points spaced from said rods with corresponding slots extending away from said rods, a pair of operating links for each lever, a pivotal connection between corresponding links with the respective levers at corresponding ends of the slots of said levers, a pivotal connection between corresponding ends of the remaining links with the respective levers adjacent the corresponding other ends of said slots, a pintle providing a fulcrum common to said levers and extending through the slots thereof, and a selector connected to said pintle and mounted for the movement thereof from one position in proximity to one of said links to a second position in proximity to the other of said links whereby said levers are simultaneously conditioned to move their respective rods in response to manipulation of one set of links or the other according to the position of the common pintle.

17. A multiple power plant comprising a plurality of engines, a plurality of output couplings, drive connections including a clutch from each engine to a coupling, a transmission having speed change gears and including a part connected to a drive connection, a cross connection between the drive connections, said cross connection including clutch parts respectively connected to said drive connections whereby each engine may be coupled to either coupling, a gear shift mechanism for the transmission, a plurality of control stations, controls for the coupling clutches comprising fluid pressure lines, cylinder and piston operators, valves and connections from said piston operators to said coupling clutches, controls for the gear shift mechanism comprising a selector, said selector being provided with a cylinder and piston operator and operating valve, said selector cylinder and piston having a fluid line interconnected with the fluid line to one of the coupling clutch fluid lines whereby the position of the coupling clutch is interlockingly related to the position of the selector.

18. A duplex truck power plant comprising a pair of engines having output shafts and clutch parts on said shafts, a transmission for each engine, a power take off coupling for each transmission and a cross connection between transmissions, said transmissions each comprising three rotors and motion transmitting means connecting said rotors for rotation in unison, one rotor in cach said transmission being provided with clutch parts coacting with respective clutch parts on said engine output shafts whereby the respective transmissions may be selectively driven by and disconnected from the respective engines, a second rotor in each transmission connected to respective power take off couplings, and a third rotor in each transmission, clutches for each said third rotor, said clutches having parts respectively connected to said third rotor and to said cross connection whereby said cross connection may selectively connect and disconnect said transmissions.

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